Games like Monster Outbreak
Games like Monster Outbreak include Terraria, The Riftbreaker, Sons Of The Forest, Raft, and Once Human. We matched them by the tags players give Monster Outbreak on Steam (Survival, Multiplayer, Hack and Slash, Crafting, and Tower Defense): closest matches first, and among equally close ones the better-known games.

Terraria
Shared: Survival · Multiplayer · Crafting

The Riftbreaker
Shared: Multiplayer · Survival · Base Building

Sons Of The Forest
Shared: Survival · Multiplayer · Co-op

Raft
Shared: Survival · Multiplayer · Co-op

Once Human
Shared: Survival · Multiplayer · Co-op

Don't Starve Together
Shared: Survival · Multiplayer · Co-op

ARK: Survival Evolved
Shared: Survival · Multiplayer · Crafting

Grounded
Shared: Survival · Co-op · Multiplayer

Valheim
Shared: Survival · Multiplayer · Crafting

Rust
Shared: Survival · Multiplayer · Crafting

Palworld
Shared: Survival · Multiplayer · Co-op

ARK: Survival Ascended
Shared: Survival · Multiplayer · Crafting

Enshrouded
Shared: Survival · Multiplayer · Base Building

Green Hell
Shared: Survival · Multiplayer · Crafting

Core Keeper
Shared: Survival · Multiplayer · Co-op

Grounded 2
Shared: Survival · Multiplayer · Co-op

Satisfactory
Shared: Multiplayer · Co-op · Base Building

7 Days to Die
Shared: Survival · Multiplayer · Base Building

Medieval Dynasty
Shared: Multiplayer · Survival · Crafting

ICARUS
Shared: Survival · Multiplayer · Crafting

Factorio
Shared: Base Building · Survival · Crafting

RuneScape: Dragonwilds
Shared: Survival · Multiplayer · Co-op

PUBG: BATTLEGROUNDS
Shared: Survival · Multiplayer · Co-op

Scrap Mechanic
Shared: Survival · Multiplayer · Co-op